With --trace-maps, we log all maps in the heap at the end of
bootstrapping. LogAllMaps scans through the heap and logs a map-create
even for all the maps in the heap. This cl updates this function to also
look for maps in the read only space.

Change-Id: I50025a909691be8dca3455c0583a0392b4756aef
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2162725Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67366}